1. Field of the Invention
The present invention relates generally to low voltage differential signaling (LVDS) structures.
2. Description of the Related Art
LVDS is a data signaling technology that provides differential current signals for high-rate data transmission. Because noise is generally equally coupled onto differential signal paths, it is substantially rejected by a remote receiver which differentially receives the LVDS signals. Accordingly, LVDS differential transmission is less susceptible to common-mode noise than typical single-ended transmission techniques. Because LVDS drivers generate low-level differential current signals, their power consumption is reduced from conventional single-ended transmission systems and is almost flat regardless of the data rate.
LVDS technology is currently standardized in the ANSI/TIA/EIA-644 Standard of the Telecommunications Industry Association/Electronics Industries Association (TIA/EIA) and in the IEEE 1596.3 Standard of the Institute for Electrical and Electronics Engineering (IEEE).
Although its low-noise, low-power characteristics make LVDS particularly suited for driving remote receivers, currently-available LVDS systems generally fail to provide means to easily accommodate different loads and readily realize selected differential currents and voltages with these loads while still maintaining a standardized common-mode level.
The present invention is directed to LVDS drivers and analog-to-digital (ADC) systems which facilitate easy alteration (e.g., replacement of a selectable resistor Rsel) of differential current levels and differential voltages in response to altered loads. In addition, these drivers and systems maintain common-mode levels in the loads which are unaffected by alterations in the loads and their associated differential current and voltage levels. These features are realized with feedback signals from high-resistance feedback resistors that are coupled across LVDS circuit bridges.